1. Field of the Invention
This invention relates to a temperature responsive valve assembly and more particularly to a temperature responsive valve assembly which selectively blocks two ports to prevent fluid flow from a common port to one of the ports while permitting flow to the other port.
2. Description of the Prior Art
Conventionally, various temperature responsive valve assemblies have been proposed in which are included a circular dish-shaped thermostatic bimetal disk movable in response to a variation in temperature to thereby connect a common port with a selected one of other ports. The valve assemblies of the above type are disclosed, for example, in U.S. Pat. Nos. 3,595,262 and 3,704,697. More particularly, the bimetal disk will snap in response to a variation in temperature from a first position wherein one port is blocked from the common port to a second position wherein the other port is blocked from the common port. This means that either of two ports has to be effectively blocked by the bimetal disk which ever position the bimetal disk occupies. This requires a precise snap range of the bimetal disk to selectively block two ports. It has been quite difficult to completely satisfy the above requirement and therefore the blocking or sealing effect has been decreased.
Furthermore, it is well known that the bimetal disk will suddenly snap during small variations in temperature. In other words, the bimetal disk will gradually change its curvature from a first position in which the bimetal disk blocks one port towards a second position in which the bimetal disk blocks the other port, when the bimetal disk senses a predetermined temperature. Thereafter, the bimetal disk will suddenly snap towards its second position and will reverse its curvature during a further small variation in temperature. Finally, the bimetal disk will gradually change its reversed curvature in accordance with a further increase in temperature. The above variation in temperature when the bimetal disk will suddenly snap is considerably small in comparison with the above variations in temperature when the bimetal disk will gradually change its curvature. Accordingly, it is desirable that the change-over valving function of the bimetal disk is completed during the above small variation in temperature in order to satisfy a good response of valving function. However, the above difficulty of the precise snap range will also adversely effect the good response of the valving portion.
In addition, in copending Patent Application Ser. No. 751,720 filed Dec. 17, 1976 by the same inventors and assignee of the present application there is disclosed an improved temperature responsive valve assembly wherein a snap range of a circular thermostatic bimetal disk can be adjustable.
However, the beforementioned temperature responsive valve assemblies do not have any means for assuring or maintaining an adjusted snap range of a bimetal disk.